Tamoxifen revolutionized personalized medicine as the first targeted therapy proven to save lives in cancer.1 The paradigm change proposed to block the breast tumor estrogen receptor (ER), apply long-term adjuvant therapy to block estrogen-stimulated recurrences,1,2 and apply the potential of tamoxifen to prevent breast cancer.3 These strategic recommendations were translated, during the past 3 decades, to clinical care.1 A meta-analysis4 of randomized clinical trials revealed that the strategic use of long-term adjuvant tamoxifen therapy is the key to therapeutic success. In addition, we now know that treating metastatic breast cancer (MBC) is only palliative at the end of life, but the same medicine saves lives if applied as long-term adjuvant therapy. Nevertheless, the question has to be asked whether the results would be the same outside the clinical trials process.